The basic mode of a rivet failure is in shear, since rivets are not generally designed to transmit direct tension loads. The function of a rivet is to fasten two plates (or panels) permanently. This can be accomplished by a cold or hot process; although, in more recent times, the cold method is preferred in industry because of the availability of efficient and fast riveting tools. Rivets are generally less expensive than threaded fasteners; although their strength in tension and shear may be lower than that of threaded fasteners. The term "bolt" can be thought of as including all threaded fasteners, including studs and machine screws. The design criteria for threaded fasteners are defined by SAE International and the American Society of Testing and Materials (ASTM). The proof load and the tensile strength of threaded fasteners are subdivided into two broad categories, depending on the type of the thread required; either course or fine threads.